EP3252856B1 - Rostfreies stahlblech für separatoren von polymerelektrolytbrennstoffzellen - Google Patents

Rostfreies stahlblech für separatoren von polymerelektrolytbrennstoffzellen Download PDF

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EP3252856B1
EP3252856B1 EP15879837.1A EP15879837A EP3252856B1 EP 3252856 B1 EP3252856 B1 EP 3252856B1 EP 15879837 A EP15879837 A EP 15879837A EP 3252856 B1 EP3252856 B1 EP 3252856B1
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Prior art keywords
stainless steel
alloy layer
separator
fuel cell
polymer electrolyte
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French (fr)
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EP3252856A4 (de
EP3252856A1 (de
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Takayoshi Yano
Shin Ishikawa
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JFE Steel Corp
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JFE Steel Corp
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M8/00—Fuel cells; Manufacture thereof
    • H01M8/02—Details
    • H01M8/0202—Collectors; Separators, e.g. bipolar separators; Interconnectors
    • H01M8/0204—Non-porous and characterised by the material
    • H01M8/0223—Composites
    • H01M8/0228—Composites in the form of layered or coated products
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
    • C25D3/00—Electroplating: Baths therefor
    • C25D3/02—Electroplating: Baths therefor from solutions
    • C25D3/56—Electroplating: Baths therefor from solutions of alloys
    • C25D3/60—Electroplating: Baths therefor from solutions of alloys containing more than 50% by weight of tin
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
    • C25D5/00—Electroplating characterised by the process; Pretreatment or after-treatment of workpieces
    • C25D5/48—After-treatment of electroplated surfaces
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
    • C25D7/00—Electroplating characterised by the article coated
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M8/00—Fuel cells; Manufacture thereof
    • H01M8/02—Details
    • H01M8/0202—Collectors; Separators, e.g. bipolar separators; Interconnectors
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M8/00—Fuel cells; Manufacture thereof
    • H01M8/02—Details
    • H01M8/0202—Collectors; Separators, e.g. bipolar separators; Interconnectors
    • H01M8/0204—Non-porous and characterised by the material
    • H01M8/0206—Metals or alloys
    • H01M8/0208—Alloys
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M8/00—Fuel cells; Manufacture thereof
    • H01M8/02—Details
    • H01M8/0202—Collectors; Separators, e.g. bipolar separators; Interconnectors
    • H01M8/0204—Non-porous and characterised by the material
    • H01M8/0206—Metals or alloys
    • H01M8/0208—Alloys
    • H01M8/021—Alloys based on iron
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M8/00—Fuel cells; Manufacture thereof
    • H01M8/02—Details
    • H01M8/0202—Collectors; Separators, e.g. bipolar separators; Interconnectors
    • H01M8/023—Porous and characterised by the material
    • H01M8/0232—Metals or alloys
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M8/00—Fuel cells; Manufacture thereof
    • H01M8/02—Details
    • H01M8/0202—Collectors; Separators, e.g. bipolar separators; Interconnectors
    • H01M8/023—Porous and characterised by the material
    • H01M8/0241—Composites
    • H01M8/0245—Composites in the form of layered or coated products
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M8/00—Fuel cells; Manufacture thereof
    • H01M8/10—Fuel cells with solid electrolytes
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M8/00—Fuel cells; Manufacture thereof
    • H01M8/10—Fuel cells with solid electrolytes
    • H01M2008/1095—Fuel cells with polymeric electrolytes
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/30—Hydrogen technology
    • Y02E60/50—Fuel cells

Definitions

  • This disclosure relates to a stainless steel sheet for a separator (bipolar plate) of a polymer electrolyte fuel cell having excellent corrosion resistance and adhesion.
  • a fuel cell generates electricity from H 2 and O 2 through an electrochemical reaction.
  • the fuel cell has a sandwich-like basic structure and includes an electrolyte membrane (ion-exchange membrane), two electrodes (fuel electrode and air electrode), gas diffusion layers for O 2 (air) and H 2 , and two separators.
  • Fuel cells are classified as phosphoric acid fuel cells, molten carbonate fuel cells, solid oxide fuel cells, alkaline fuel cells, and polymer electrolyte fuel cells (PEFCs; proton-exchange membrane fuel cells) according to the type of electrolyte membrane used. Development of each of these types of fuel cells is ongoing.
  • PEFCs polymer electrolyte fuel cells
  • polymer electrolyte fuel cells have, for example, the following advantages over other fuel cells.
  • a polymer electrolyte fuel cell generates electricity from H 2 and O 2 via a polymer membrane.
  • a membrane-electrode joined body 1 is sandwiched between gas diffusion layers 2 and 3 (for example, carbon paper) and separators 4 and 5, forming a single component (referred to as a "single cell").
  • An electromotive force is generated between the separators 4 and 5.
  • the membrane-electrode joined body 1 is called a membrane-electrode assembly (MEA).
  • MEA membrane-electrode assembly
  • the membrane-electrode joined body 1 is an assembly of a polymer membrane and an electrode material such as a carbon black-supported platinum catalyst on the front and back surfaces of the membrane, and has a thickness of the order of tens to hundreds of micrometers.
  • the gas diffusion layers 2 and 3 are often integrated with the membrane-electrode joined body 1.
  • the separators 4 and 5 are required to function not only as
  • the separators 4 and 5 need to have excellent durability and electrical conductivity.
  • a durability of about 5,000 hours is expected in the case of a polymer electrolyte fuel cell that is used as a power source in an electric vehicle, whereas a durability of about 40,000 hours is expected in the case of a polymer electrolyte fuel cell that is used as a home stationary generator or the like. Therefore, the separators are required to have sufficient corrosion resistance for withstanding long-term generating, because dissolved metal ions due to corrosion may reduce the proton conductivity of the polymer membrane (electrolyte membrane).
  • the contact resistance between the separator and the gas diffusion layer is preferably as low as possible, because an increase in contact resistance between the separator and the gas diffusion layer lowers generation efficiency of the polymer electrolyte fuel cell. In other words, lower contact resistance between the separator and the gas diffusion layer contributes to better power generation characteristics.
  • Patent Literature (PTL) 1 discloses a technique of using, for separators, a metal such as stainless steel or a titanium alloy that easily forms a passive film. The formation of the passive film, however, causes an increase in contact resistance, and leads to lower generation efficiency. These metal materials have thus been pointed out to have problems that require mitigation such as high contact resistance and poor corrosion resistance as compared with graphite materials.
  • PTL 2 discloses a technique of plating the surface of a metal separator such as an austenitic stainless steel sheet (SUS304) with gold to reduce the contact resistance and ensure high output.
  • a metal separator such as an austenitic stainless steel sheet (SUS304)
  • SUS304 austenitic stainless steel sheet
  • a thin gold plating is susceptible to formation of pinholes, whereas a thick gold plating is problematic in terms of cost.
  • this film is also referred to simply as a "Sn alloy layer"
  • this film is also referred to simply as a "Sn alloy layer”
  • defects may be generated in the Sn alloy layer as a result of surface defects, such as scratches and surface roughness, generated during production of the metal substrate or forming of the metal substrate into a desired shape.
  • the exposed part of the substrate may be more susceptible to corrosion if the use environment of the fuel cell separator is contaminated with chloride ions from the external environment. Moreover, this corrosion may lead to formation of a hole in the substrate.
  • FIG. 1 is a schematic view illustrating the basic structure of a fuel cell.
  • SUS447J1 (Cr: 30 mass%, Mo: 2 mass%)
  • SUS445J1 (Cr: 22 mass%, Mo: 1 mass%)
  • SUS443J1 (Cr: 21 mass%)
  • SUS439 (Cr: 18 mass%)
  • SUS316L (Cr: 18 mass%, Ni: 12 mass%, Mo: 2 mass%), or the like is suitable.
  • the sheet thickness of the stainless steel sheet for a separator is preferably 0.03 mm or more.
  • the sheet thickness of the stainless steel sheet for a separator is preferably 0.3 mm or less. This is in view of the installation space and weight when stacking fuel cells. If the sheet thickness of the stainless steel sheet for a separator is less than 0.03 mm, the production efficiency of the stainless steel sheet declines. On the other hand, if the sheet thickness of the stainless steel sheet for a separator is more than 0.3 mm, the installation space and weight when stacking fuel cells increases.
  • the sheet thickness of the stainless steel sheet for a separator is more preferably 0.03 mm or more and 0.1 mm or less.
  • Ni 3 Sn 2 Ni 3 Sn 4 , FeSn, or FeSn 2 is preferable.
  • the intermetallic compound Ni 3 Sn 2 is particularly preferable.
  • Bonds such as Sn-Ni bonds or Sn-Fe bonds in a Sn alloy are more stable than Sn-Sn bonds in simple metal Sn, which improves corrosion resistance.
  • Ni 3 Sn 2 has a formation temperature in a high temperature range of 790 °C or higher according to a binary alloy phase diagram of Ni-Sn and forms very stable Sn-Ni bonds, which is thought to contribute to excellent corrosion resistance.
  • the thickness of the Sn alloy layer is preferably 5 ⁇ m or less in consideration of installation space and weight when stacking fuel cells. However, if the thickness of the Sn alloy layer is less than 0.1 ⁇ m, coating defects increase and corrosion resistance tend to deteriorate. Accordingly, the thickness of the Sn alloy layer is preferably 0.1 ⁇ m or more. The thickness of the Sn alloy layer is more preferably 0.5 ⁇ m or more. The thickness of the Sn alloy layer is more preferably 3 ⁇ m or less.
  • a plating method is suitable for the formation of the Sn alloy layer on the surface of the stainless steel substrate.
  • a conventionally known plating method may be used to immerse the substrate in a plating bath adjusted to a predetermined composition and electroplate the substrate.
  • the Sn alloy layer may be formed after removing a passive film at the surface of the substrate by electrolytic treatment or the like.
  • microcracks are formed in the Sn alloy layer in an amount of 10 or more microcracks per cm 2 . This enables corrosion current to be dispersed in the microcracks and effectively inhibits concentration of the corrosion current even when a defect is generated in the Sn alloy layer, leading to exposure of the stainless steel substrate, and when an environment arises in which localized lowering of pH and concentration of chloride ions easily occur. Consequently, hole formation in the stainless steel substrate can be effectively prevented.
  • the Sn alloy layer preferably includes 100 or more microcracks per cm 2 , and more preferably includes 1,000 or more microcracks per cm 2 . However, if the Sn alloy layer includes more than 10,000 microcracks per cm 2 , the Sn alloy layer may peel more easily from the substrate and corrosion resistance may deteriorate. Therefore, the Sn alloy layer preferably includes 10,000 or fewer microcracks per cm 2 . The Sn alloy layer more preferably includes 8,000 or fewer microcracks per cm 2 .
  • a microcrack is defined as a crack having a crack width that is at least 0.1 times the thickness of the Sn alloy layer and no more than 10 ⁇ m.
  • a microcrack having a crack width of less than 0.1 times the thickness of the Sn alloy layer does not reach the base material and does not enable dispersion of the corrosion current.
  • the Sn alloy layer peels more easily from the substrate if numerous cracks having a crack width of more than 10 ⁇ m are present.
  • the crack length is normally about 1 ⁇ m to 500 ⁇ m, but is not specifically limited to this range.
  • the crack width of the microcracks can be determined by, for example, observing the surface of the Sn alloy layer at ⁇ 5,000 magnification using a scanning electron microscope (SEM) and measuring the crack width (opening width) of an observed microcrack.
  • the crack length can be determined by measuring the length of a line segment linking the ends of a microcrack observed in the same manner as described above (i.e., the length of a straight line between the ends of the crack). It should be noted that a branched crack or a crack having a shape formed through joining of cracks to one another is considered to be a single microcrack so long as it is connected.
  • the crack length of this kind of microcrack is taken to be the length of a longest line segment among line segments linking ends of the crack.
  • Examples of methods that can be used to form the microcracks in the Sn alloy layer include a method in which a high-stress strike is used as a surface treatment, a method in which rolling by leveler, a skin pass rolling mill, or the like is carried out after coating, and a method in which strain is applied through bending.
  • microcrack formation conditions depending on the material and thickness of the stainless steel substrate, the thickness of the Sn alloy layer, and so forth.
  • a stainless steel sheet obtained by using a corrugator machine to form a wave shape difference in height between protrusion and adjacent recess: 1.0 mm, distance between protrusions: 2.5 mm
  • a stainless steel substrate (SUS447J1) of 0.05 mm in thickness and by forming a Sn alloy layer of 1 ⁇ m to 2 ⁇ m in thickness on the surface thereof, microcracks can be appropriately formed in the Sn alloy layer through rolling with a load of 0.5 MPa to 10 MPa (more suitably, 1 MPa to 5 MPa).
  • a strike layer may be formed between the substrate made of stainless steel and the Sn alloy layer to improve adhesion.
  • a strike layer of Ni, Ni-P, Cu, Ag, Au, or the like may be formed by a commonly known technique and then the Sn alloy layer may be formed thereon.
  • the strike layer may be formed after removing a passive film at the surface of the substrate by electrolytic treatment or the like.
  • the coating weight of the strike layer is preferably 0.001 g/m 2 or more.
  • the coating weight of the strike layer is preferably 1 g/m 2 or less. This is from a viewpoint of achieving a balance of adhesion and corrosion resistance.
  • the coating weight of the strike layer is more preferably 0.003 g/m 2 or more.
  • the coating weight of the strike layer is more preferably 0.5 g/m 2 or less.
  • the coating weight of the strike layer is even more preferably 0.003 g/m 2 or more and 0.3 g/m 2 or less.
  • the coating weight being within any of the ranges set forth above, the effect of corrosion current dispersion to the microcracks can be maintained even when a strike layer such as described is formed.
  • the surface of the Sn alloy layer may be coated with a Sn-containing oxide layer. This further improves corrosion resistance of the Sn alloy layer during long-term use in the use environment of a separator.
  • the Sn-containing oxide layer with which the surface of the Sn alloy layer is coated is not a natural oxide layer formed in the atmospheric environment but an oxide layer intentionally formed by a process such as immersion in an acidic solution. Note that the thickness of a natural oxide layer is typically about 2 nm to 3 nm.
  • the main component of the Sn-containing oxide layer is preferably SnO 2 .
  • the thickness of the Sn-containing oxide layer is preferably 5 nm or more.
  • the thickness of the Sn-containing oxide layer is preferably 50 nm or less.
  • the thickness of the Sn-containing oxide layer is more preferably 10 nm or more.
  • the thickness of the Sn-containing oxide layer is more preferably 30 nm or less.
  • An excessively thick Sn-containing oxide layer reduces conductivity. On the other hand, an excessively thin Sn-containing oxide layer does not achieve an effect of improving corrosion resistance in the use environment of a separator.
  • the Sn-containing oxide layer may be formed by a method of immersion in an acidic aqueous solution having oxidizing ability such as hydrogen peroxide or nitric acid, or a method of electrochemical anode electrolytic treatment.
  • an acidic aqueous solution having oxidizing ability such as hydrogen peroxide or nitric acid
  • electrochemical anode electrolytic treatment Other examples include physical vapor deposition (PVD), chemical vapor deposition (CVD), and coating.
  • the Sn-containing oxide layer normally has an extremely small thickness of about 5 nm to 50 nm, the Sn-containing oxide layer does not influence the effect of the microcracks or observation of the microcracks.
  • a conductive layer with low electrical resistance may be further formed on the Sn alloy layer to improve conductivity, which is one of the required properties of a separator.
  • the Sn alloy layer or the Sn-containing oxide layer may be coated with a metal layer, a conductive polymer layer, an alloy layer containing conductive particles, or a polymer layer containing conductive particles to reduce the contact resistance.
  • separators of polymer electrolyte fuel cells are used in a severe corrosion environment that has a temperature of about 80 °C and a pH of about 3, and that may also be contaminated with chloride ions from the external environment. Therefore, separators of polymer electrolyte fuel cells are required to have excellent anti-corrosion properties. In view of these required properties, the following evaluation was conducted on the subsequently described samples.
  • Each sample was immersed in a sulfuric acid aqueous solution containing 30 ppm of chloride ions at a temperature of 80 °C and a pH of 3, and was subjected to application of a constant potential of 0.9 V (vs. SHE) for 20 hours using Ag/AgCl (saturated KCl) as a reference electrode. Once 20 hours has passed, the formation of holes into the stainless steel substrate was inspected by eye. The current density after 20 hours was also measured. Corrosion resistance were evaluated based on the following criteria.
  • a hole is formed in the stainless steel substrate and/or the current density after 20 hours is 0.2 ⁇ A/cm 2 or more.
  • SUS447J1 (Cr: 30 mass%, Mo: 2 mass%), SUS445J1 (Cr: 22 mass%, Mo: 1 mass%), and SUS316L (Cr: 18 mass%, Ni: 12 mass%, Mo: 2 mass%) having a sheet thickness of 0.05 mm was corrugated into a wave shape (difference in height between protrusion and adjacent recess: 1.0 mm, protrusion and recess distance: 2.5 mm).
  • the corrugated product was used as a stainless steel substrate.
  • the corrugation imitated the shape of a typical separator material and also imitated generation of surface defects, such as scratches and surface roughness, that are generated in production of the stainless steel substrate or forming of the stainless steel substrate into a desired shape.
  • the stainless steel substrate obtained as described above was subjected to appropriate pretreatment such as degreasing. Thereafter, a Sn alloy layer having the average thickness shown in Table 1 was formed on the stainless steel substrate using the following plating bath composition and plating conditions to obtain a stainless steel sheet for a separator.
  • a strike layer with the average coating weight shown in Table 1 was formed on the stainless steel substrate using the following plating bath composition and plating conditions, prior to formation of the Sn alloy layer.
  • a Sn-containing oxide layer was formed on the surface of the Sn alloy layer by, after formation of the Sn alloy layer, passing current through the resultant stainless steel sheet with a current density of +0.5 mA/cm 2 for 5 minutes while in a sulfuric acid aqueous solution of a temperature of 60 °C and a pH of 2.
  • microcrack formation treatment by rolling under a load of 0.5 MPa to 20 MPa to form microcracks.
  • the microcrack formation treatment was carried out either after formation of the Sn alloy layer or after formation of the Sn-containing oxide layer.
  • the coating weight of the strike layer, the average thickness of the Sn alloy layer, and the average thickness of the Sn-containing oxide layer were each regulated by determining the relationship with the plating time or the anode electrolysis time beforehand.
  • the average number of microcracks was measured by the following method. First, each sample obtained by forming the Sn alloy layer on the surface of the stainless steel substrate (thickness: 0.05 mm) and then performing the above-described microcrack formation treatment was cut to about 20 mm W ⁇ 20 mm L. Next, the surface of the Sn alloy layer in the cut sample was randomly observed at ⁇ 100 to ⁇ 5,000 magnification using a scanning electron microscope (SEM). The number of observed microcracks was counted and the number of microcracks per 1 cm 2 was calculated. This measurement was performed on five samples that were each cut to the shape described above from the same sample obtained after Sn alloy layer formation and microcrack formation treatment.
  • SEM scanning electron microscope
  • An average value for these five samples was taken to be the average number of microcracks. Note that only cracks having a width of at least 0.1 times the thickness of the Sn alloy layer and no more than 10 ⁇ m, and having a crack length of at least 1 ⁇ m and no more than 500 ⁇ m, were determined to be microcracks. Furthermore, a branched crack or a crack having a shape formed through joining of cracks to one another was determined to be a single microcrack so long as it was connected.
  • the coating weight of the strike layer was measured by the following method. First, each sample obtained by forming the strike layer on the surface of the stainless steel substrate (thickness: 0.05 mm) was cut to about 50 mm W ⁇ 50 mm L. The lengths of two sides of the cut sample were measured by a vernier caliper and the sample area was calculated. The sample was then immersed for 10 minutes in a solution in which the strike layer could be dissolved (a known dissociation solution may be used, such as 30% nitric acid for Ni or Ni-P strike) to dissolve the strike layer. One or more constituent elements of the strike layer dissolved in the solution were quantified using an inductively coupled plasma (ICP) emission spectrometric analyzer, and this quantity was divided by the sample area to calculated the coating weight (g/m 2 ).
  • ICP inductively coupled plasma
  • the average thickness of the Sn alloy layer was measured by the following method. First, each sample obtained by forming the Sn alloy layer on the surface of the substrate (thickness: 0.05 mm) was cut to about 10 mm W ⁇ 15 mm L. The sample was then embedded in resin, polished in the cross section, and observed using a scanning electron microscope (SEM) to measure the thickness of the Sn alloy layer. The measurement of the thickness of the Sn alloy layer was performed on 10 samples that were each cut to the shape described above from the same sample obtained after Sn alloy layer formation. An average value for the 10 samples was taken to be the average thickness of the Sn alloy layer.
  • SEM scanning electron microscope
  • composition of the Sn alloy layer was identified by an energy-dispersive X-ray spectrometer (EDX) and X-ray diffractometer (XRD) used in the SEM observation.
  • EDX energy-dispersive X-ray spectrometer
  • XRD X-ray diffractometer
  • the average thickness of the Sn-containing oxide layer was measured by the following method. First, each sample obtained by forming the strike layer, the Sn alloy layer, and the Sn-containing oxide layer on the surface of the substrate (thickness: 0.05 mm) was processed by a focused ion beam to prepare a thin film for cross-sectional observation. The produced thin film for cross-sectional observation was then observed using a transmission electron microscope (TEM) to measure the average thickness of the Sn-containing oxide layer. In the measurement of the thickness of the Sn-containing oxide layer, the thickness of the Sn-containing oxide layer in the prepared thin film for cross-sectional observation was measured at three locations. An average value for the three locations was taken to be the average thickness of the Sn-containing oxide layer.
  • TEM transmission electron microscope
  • composition of the oxide layer was identified by an energy-dispersive X-ray spectrometer (EDX) and X-ray photoelectron spectrometer (XPS) used in the TEM observation.
  • EDX energy-dispersive X-ray spectrometer
  • XPS X-ray photoelectron spectrometer
  • Nickel chloride 240 g/L Hydrochloric acid: 125 mL/L Temperature: 50 °C Current density: 5 A/dm 2
  • Nickel sulfate 1 mol/L Nickel chloride: 0.1 mol/L Boric acid: 0.5 mol/L Sodium phosphite: 0.05 mol/L to 5 mol/L Temperature: 50 °C Current density: 5 A/dm 2
  • Nickel chloride 0.15 mol/L Tin chloride: 0.15 mol/L Potassium pyrophosphate: 0.45 mol/L Glycine: 0.15 mol/L Temperature: 60 °C Current density: 1 A/dm 2
  • Nickel chloride 0.15 mol/L Tin chloride: 0.30 mol/L Potassium pyrophosphate: 0.45 mol/L Temperature: 60 °C Current density: 1 A/dm 2
  • a plating bath composition other than the above may be used according to a commonly known plating method as long as a desired plating can be formed.
  • Table 1 summarizes the evaluation results of corrosion resistance (stability in use environment of separator) for each sample obtained as described above.
  • the table reveals the following points.

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Claims (5)

  1. Edelstahlblech für einen Separator einer Polymer-Elektrolyt-Brennstoffzelle, umfassend:
    ein Substrat aus Edelstahl; und
    eine Sn-Legierungsschicht, mit der eine Oberfläche des Substrats beschichtet ist,
    wobei
    d ie Sn-Legierungsschicht 10 oder mehr Mikrorisse pro cm2 beinhaltet.
  2. Edelstahlblech für einen Separator einer Polymer-Elektrolyt-Brennstoffzelle gemäß Anspruch 1, wobei
    die Sn-Legierungsschicht zumindest ein Element ausgewählt aus Ni und Fe beinhaltet.
  3. Edelstahlblech für einen Separator einer Polymer-Elektrolyt-Brennstoffzelle gemäß Anspruch 1 oder 2, wobei
    die Sn-Legierungsschicht Ni3Sn2 beinhaltet.
  4. Edelstahlblech für einen Separator einer Polymer-Elektrolyt-Brennstoffzelle gemäß einem der Ansprüche 1 bis 3, weiterhin umfassend
    eine Schlagschicht zwischen der Sn-Legierungsschicht und dem Substrat aus Edelstahl.
  5. Edelstahlblech für einen Separator einer Polymer-Elektrolyt-Brennstoffzelle gemäß einem der Ansprüche 1 bis 4, weiterhin umfassend
    eine Sn-beinhaltende Oxidschicht auf einer Oberfläche der Sn-Legierungsschicht.
EP15879837.1A 2015-01-29 2015-12-18 Rostfreies stahlblech für separatoren von polymerelektrolytbrennstoffzellen Active EP3252856B1 (de)

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US4865700A (en) 1987-02-13 1989-09-12 M&T Chemicals Inc. Plating bath and process for making microporous chromium deposits
JP3460346B2 (ja) 1994-12-26 2003-10-27 富士電機株式会社 固体高分子電解質型燃料電池
JP3854682B2 (ja) 1997-02-13 2006-12-06 アイシン高丘株式会社 燃料電池用セパレータ
AUPQ653700A0 (en) * 2000-03-28 2000-04-20 Ceramic Fuel Cells Limited Surface treated electrically conductive metal element and method of forming same
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JP5412462B2 (ja) * 2011-04-19 2014-02-12 日本パーカライジング株式会社 金属材料用耐食合金コーティング膜及びその形成方法
JP5928364B2 (ja) 2012-04-25 2016-06-01 Ｊｆｅスチール株式会社 固体高分子形燃料電池のセパレータ用金属板
JP6004181B2 (ja) 2013-01-18 2016-10-05 スズキ株式会社 陽極酸化皮膜及びその製造方法

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EP3252856A4 (de) 2017-12-06
JPWO2016120938A1 (ja) 2017-04-27
EP3252856A1 (de) 2017-12-06
CN107210455B (zh) 2020-09-04
WO2016120938A1 (ja) 2016-08-04
KR101963992B1 (ko) 2019-03-29
KR20170095298A (ko) 2017-08-22
CN107210455A (zh) 2017-09-26
MX2017009672A (es) 2017-10-12
TWI617078B (zh) 2018-03-01
US20180026276A1 (en) 2018-01-25
WO2016120938A8 (ja) 2017-05-18
JP6015880B1 (ja) 2016-10-26
US10256478B2 (en) 2019-04-09
TW201637270A (zh) 2016-10-16

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